Coated article having antibacterial effect and method for making the same

ABSTRACT

A coated article is described. The coated article includes a substrate, a bonding layer formed on the substrate, a plurality of nickel-chromium-nitrogen layers and a plurality of silver-cerium alloy layers formed on the bonding layer. The bonding layer is a nickel-chromium layer. Each nickel-chromium-nitrogen layer interleaves with one silver-cerium alloy layer. One of the nickel-chromium-nitrogen layers is directly formed on the bonding layer. A method for making the coated article is also described.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is one of the five related co-pending U.S. patentapplications listed below. All listed applications have the sameassignee. The disclosure of each of the listed applications isincorporated by reference into the other listed applications.

Attorney Docket No. Title Inventors US 37027 COATED ARTICLE HAVINGHSIN-PEI ANTIBACTERIAL EFFECT AND METHOD CHANG FOR MAKING THE SAME etal. US 37028 COATED ARTICLE HAVING HSIN-PEI ANTIBACTERIAL EFFECT ANDMETHOD CHANG FOR MAKING THE SAME et al. US 37029 COATED ARTICLE HAVINGHSIN-PEI ANTIBACTERIAL EFFECT AND METHOD CHANG FOR MAKING THE SAME etal. US 37138 COATED ARTICLE HAVING HSIN-PEI ANTIBACTERIAL EFFECT ANDMETHOD CHANG FOR MAKING THE SAME et al. US 38935 COATED ARTICLE HAVINGHSIN-PEI ANTIBACTERIAL EFFECT AND METHOD CHANG FOR MAKING THE SAME etal.

BACKGROUND

1. Technical Field

The present disclosure relates to coated articles, particularly to acoated article having an antibacterial effect and a method for makingthe coated article.

2. Description of Related Art

To make the living environment more hygienic and healthy, a variety ofantibacterial products have been produced by coating antibacterial metalfilms on the substrates of the products. The metal may be copper (Cu),zinc (Zn), or silver (Ag). However, the coated metal films are soft andbond poorly to the substrate, so the metal films are prone to abrasion.Moreover, the metal ions within the metal films rapidly dissolve fromkilling bacterium, so the metal films have a short lifespan.

Therefore, there is room for improvement within the art.

BRIEF DESCRIPTION OF THE FIGURES

Many aspects of the disclosure can be better understood with referenceto the following figures. The components in the figures are notnecessarily drawn to scale, the emphasis instead being placed uponclearly illustrating the principles of the disclosure. Moreover, in thedrawings like reference numerals designate corresponding partsthroughout the several views.

FIG. 1 is a cross-sectional view of an exemplary embodiment of a coatedarticle.

FIG. 2 is an overhead view of an exemplary embodiment of a vacuumsputtering device.

DETAILED DESCRIPTION

FIG. 1 shows a coated article 10 according to an exemplary embodiment.The coated article 10 includes a substrate 11, a bonding layer 13 formedon the substrate 11, a plurality of nickel-chromium-nitrogen (Ni—Cr—N)layers 15 and a plurality of silver-cerium (Ag—Ce) alloy layers 17formed on the bonding layer 13. Each Ni—Cr—N layer 15alternates/interleaves with one Ag—Ce alloy layer 17. One of the Ni—Cr—Nlayers 15 is directly formed on the bonding layer 13. Furthermore, oneof the Ni—Cr—N layers 15 forms the outermost layer of the coated article10. Therefore, there is typically one more Ni—Cr—N layer 15 than thereare Ag—Ce alloy layers 17. The total thickness of the Ni—Cr—N layers 15and the Ag—Ce alloy layers 17 may be about 2 μm-3.2 μm. The total numberof the Ni—Cr—N layers 15 may be about 15 layers to about 21 layers. Thetotal number of the Ag—Ce alloy layers 17 may be about 14 layers toabout 20 layers.

The substrate 11 may be made of stainless steel, but is not limited tostainless steel.

The bonding layer 13 may be a nickel-chromium (Ni—Cr) alloy layer formedon the substrate 11 by vacuum sputtering. The bonding layer 13 has athickness of about 150 nm-250 nm.

The Ni—Cr—N layers 15 may be formed by vacuum sputtering. Each Ni—Cr—Nlayer 15 may have a thickness of about 40 nm-80 nm. Each Ni—Cr—N layer15 contains by atomic percentage, about 30%-45% nickel, about 40%-55%chromium, and about 5%-15% nitrogen. The Ni—Cr—N layers 15 have a porousstructure. Furthermore, the Ni—Cr—N layers 15 are hard coatings andabrasion resistant, which provide the coated article 10 with highhardness and good abrasion resistance.

The Ag—Ce alloy layers 17 may be formed by vacuum sputtering. Each Ag—Cealloy layer 17 may have a thickness of about 40 nm-80 nm. Each Ag—Cealloy layer 17 contains about 20%-30% cerium and 70%-80% silver byatomic percentage. Each Ag—Ce alloy layer 17 has a portion that imbedsin the porous structure of the adjacent two Ni—Cr—N layers 15. As such,the Ag—Ce alloy layers 17 are securely attached to the Ni—Cr—N layers 15and the silver or cerium ions with an antibacterial property within theAg—Ce alloy layers 17 will not be dissolved rapidly, thus the Ag—Cealloy layers 17 have long-lasting antibacterial effect. Furthermore, theoutermost Ni—Cr—N layer 15 will protect the Ag—Ce alloy layers 17 fromabrasion, which further prolongs the antibacterial effect of the coatedarticle 10.

A method for making the coated article 10 may include the followingsteps:

The substrate 11 is pre-treated, such pre-treating process may includethe following steps:

The substrate 11 is cleaned in an ultrasonic cleaning device (not shown)filled with ethanol or acetone.

The substrate 11 is plasma cleaned. Referring to FIG. 2, the substrate11 may be positioned in a coating chamber 21 of a vacuum sputteringdevice 20. The coating chamber 21 is fixed with nickel-chromium (Ni—Cr)alloy targets 23 and silver-cerium (Ag—Ce) alloy targets 25. The masspercentage of nickel and chromium in the Ni—Cr alloy targets 23 may berespectively about 20%-40% and about 60%-80%. The mass percentage ofsilver and cerium in the Ag—Ce alloy targets 25 may be respectivelyabout 40%-60%. The coating chamber 21 is then evacuated to about4.0×10⁻³ Pa. Argon gas (Ar) having a purity of about 99.999% may be usedas a working gas and is fed into the coating chamber 21 at a flow rateof about 500 standard-state cubic centimeters per minute (sccm). Thesubstrate 11 may have a bias voltage of about −200 V to about −350 V,then high-frequency voltage is produced in the coating chamber 21 andthe argon gas is ionized to plasma. The plasma then strikes the surfaceof the substrate 11 to clean the surface of the substrate 11. Plasmacleaning of the substrate 11 may take about 3 minutes (min)-10 min. Theplasma cleaning process enhances the bond between the substrate 11 andthe bonding layer 13. The Ni—Cr alloy targets 23 and the Ag—Ce alloytargets 25 are unaffected by the pre-cleaning process.

The bonding layer 13 may be magnetron sputtered on the pretreatedsubstrate 11 by using a direct current power on the nickel-chromiumalloy targets 23. Magnetron sputtering of the bonding layer 13 isimplemented in the coating chamber 21. The inside of the coating chamber21 is heated to about 70° C.-90° C. Argon gas may be used as a workinggas and is fed into the coating chamber 21 at a flow rate of about 350sccm-500 sccm. The direct current power is applied to thenickel-chromium alloy targets 23, and nickel atoms and chromium atomsare sputtered off from the nickel-chromium alloy targets 23 to depositthe bonding layer 13 on the substrate 11. During the depositing process,the substrate 11 may have a bias voltage of about −100 V to about −150V. Depositing of the bonding layer 13 may take about 5 min-10 min.

One of the Ni—Cr—N layers 15 may be magnetron sputtered on the bondinglayer 13 by using a direct current power on the nickel-chromium alloytargets 23. Magnetron sputtering of the Ni—Cr—N layer 15 is implementedin the coating chamber 21. The internal temperature of the coatingchamber 21 is maintained at about 70° C.-90° C. Nitrogen (N₂) may beused as a reaction gas and is fed into the coating chamber 21 at a flowrate of about 45 sccm-120 sccm. Argon gas may be used as a working gasand is fed into the coating chamber 21 at a flow rate of about 400sccm-500 sccm. The direct current power at a level of about 7 kilowatt(KW) to about 11 KW is applied on the nickel-chromium alloy targets 23,and then nickel atoms and chromium atoms are sputtered off from thenickel-chromium alloy targets 23. The nickel atoms, chromium atoms andnitrogen atoms are ionized in an electrical field in the coating chamber21. The ionized nickel and chromium atoms then chemically react with theionized nitrogen to deposit the Ni—Cr—N layer 15 on the bonding layer13. During the depositing process, the substrate 11 may have a directcurrent bias voltage of about −50 V to about −100 V. Depositing of theNi—Cr—N layer 15 may take about 5 min-7 min.

One of the Ag—Ce alloy layers 17 may be magnetron sputtered on theNi—Cr—N layer 15 by using a direct current power of 8 KW-10 KW on theAg—Ce alloy targets 25. Magnetron sputtering of the Ag—Ce alloy layer 17is implemented in the coating chamber 21. The internal temperature ofthe coating chamber 21 is maintained at about 70° C.-90° C. Argon gasmay be used as a working gas and is fed into the coating chamber 21 at aflow rate of about 400 sccm-500 sccm. The direct current power isapplied on the Ag—Ce alloy targets 25, and then Ag atoms and Ce atomsare sputtered off from the Ag—Ce alloy targets 25 to deposit the Ag—Cealloy layer 17 on the Ni—Cr—N layer 15. During the depositing process,the substrate 11 may have a direct current bias voltage of about −50 Vto about −100 V. Depositing of the Ag—Ce alloy layer 17 may take about 5min-7 min.

The steps of magnetron sputtering the Ni—Cr—N layer 15 and the Ag—Cealloy layer 17 are repeated about 13-19 times to form the coated article10. In this embodiment, one more Ni—Cr—N layer 15 may be magnetronsputtered on the Ag—Ce alloy layer 17 and the Ni—Cr—N layer 15 forms theoutermost layer of the coated article 10.

Specific examples of making the coated article 10 are described asfollows. The pre-treating process of ultrasonic cleaning the substrate11 in these specific examples may be substantially the same aspreviously described so it is not described here again. Additionally,the magnetron sputtering processes of the bonding layer 13, Ni—Cr—Nlayer 15, and Ag—Ce alloy layer 17 in the specific examples aresubstantially the same as described above, and the specific examplesmainly emphasize the different process parameters of making the coatedarticle 10.

Example 1

The substrate 11 is made of stainless steel.

Plasma cleaning of the substrate 11: the flow rate of Ar is 500 sccm;the substrate 11 has a bias voltage of −200 V; plasma cleaning of thesubstrate 11 takes 5 min.

Sputtering to form the bonding layer 13 on the substrate 11: the flowrate of Ar is 420 sccm; the substrate 11 has a bias voltage of −100 V;the Ni—Cr alloy targets 23 are applied with a power of 7 KW; the masspercentage of nickel in the Ni—Cr alloy target 23 is 35%; the internaltemperature of the coating chamber 21 is 80° C.; sputtering of thebonding layer 13 takes 6 min; the bonding layer 13 has a thickness of185 nm.

Sputtering to form Ni—Cr—N layer 15 on the bonding layer 13: the flowrate of Ar is 400 sccm, the flow rate of N₂ is 60 sccm; the substrate 11has a bias voltage of −80 V; the Ni—Cr alloy targets 23 are applied witha power of 8 KW; the internal temperature of the coating chamber 21 is80° C.; sputtering of the Ni—Cr—N layer 15 takes 7 min; the Ni—Cr—Nlayer 15 has a thickness of 75 nm.

Sputtering to form Ag—Ce layer 17 on the Ni—Cr—N layer 15: the flow rateof Ar is 400 sccm; the substrate 11 has a bias voltage of −80 V; theAg—Ce alloy targets 25 are applied with a power of 8 KW; the masspercentage of silver in the Ag—Ce alloy target 25 is 45%; the internaltemperature of the coating chamber 21 is 80° C.; sputtering of the Ag—Celayer 17 takes 7 min; the Ag—Ce layer 17 has a thickness of 70 nm.

The step of sputtering the Ni—Cr—N layer 15 is repeated 17 times, andthe step of sputtering the Ag—Ce alloy layer 17 is repeated 16 times.

Example 2

The substrate 11 is made of stainless steel.

Plasma cleaning of the substrate 11: the flow rate of Ar is 500 sccm;the substrate 11 has a bias voltage of −200 V; plasma cleaning of thesubstrate 11 takes 5 min.

Sputtering to form the bonding layer 13 on the substrate 11: the flowrate of Ar is 420 sccm; the substrate 11 has a bias voltage of −100 V;the Ni—Cr alloy targets 23 are applied with a power of 7 KW; the masspercentage of nickel in the Ni—Cr alloy target 23 is 40%; the internaltemperature of the coating chamber 21 is 80° C.; sputtering of thebonding layer 13 takes 5 min; the bonding layer 13 has a thickness of185 nm.

Sputtering to form Ni—Cr—N layer 15 on the bonding layer 13: the flowrate of Ar is 400 sccm, the flow rate of N₂ is 100 sccm; the substrate11 has a bias voltage of −80 V; the Ni—Cr alloy targets 23 are appliedwith a power of 7 KW; the internal temperature of the coating chamber 21is 80° C.; sputtering of the Ni—Cr—N layer 15 takes 5 min; the Ni—Cr—Nlayer 15 has a thickness of 60 nm.

Sputtering to form Ag—Ce layer 17 on the Ni—Cr—N layer 15: the flow rateof Ar is 400 sccm; the substrate 11 has a bias voltage of −80 V; theAg—Ce alloy targets 25 are applied with a power of 8 KW; the masspercentage of silver in the Ag—Ce alloy target 25 is 45%; the internaltemperature of the coating chamber 21 is 80° C.; sputtering of the Ag—Celayer 17 takes 5 min; the Ag—Ce layer 17 has a thickness of 65 nm.

The step of sputtering the Ni—Cr—N layer 15 is repeated 17 times, andthe step of sputtering the Ag—Ce alloy layer 17 is repeated 16 times.

An antibacterial performance test has been performed on the coatedarticles 10 described in the above examples 1-2. The test was carriedout as follows:

Bacteria was firstly dropped on the coated article 10 and then coveredby a sterilization film and put in a sterilization culture dish forabout 24 hours at a temperature of about 37±1° C. and a relativehumidity (RH) of more than 90%. Secondly, the coated article 10 wasremoved from the sterilization culture dish, and the surface of thecoated article 10 and the sterilization film were rinsed using 20milliliter (ml) wash liquor. The wash liquor was then collected in anutrient agar to inoculate the bacteria for about 24 hours to 48 hoursat about 37±1° C. After that, the number of surviving bacteria wascounted to calculate the bactericidal effect of the coated article 10.

The test result indicated that the bactericidal effect of the coatedarticle 10 with regard to escherichia coli, salmonella, andstaphylococcus aureus was no less than 99.999%. Furthermore, afterhaving been immersed in water for about three months at about 37±1° C.,the bactericidal effect of the coated article 10 on escherichia coli,salmonella, and staphylococcus aureus was no less than 95%.

It is believed that the exemplary embodiment and its advantages will beunderstood from the foregoing description, and it will be apparent thatvarious changes may be made thereto without departing from the spiritand scope of the disclosure or sacrificing all of its advantages, theexamples hereinbefore described merely being preferred or exemplaryembodiment of the disclosure.

What is claimed is:
 1. A coated article, comprising: a substrate; abonding layer formed on the substrate, the bonding layer being anickel-chromium alloy layer; and a plurality of alternatingnickel-chromium-nitrogen layers and silver-cerium alloy layers formed onthe bonding layer, one of the nickel-chromium-nitrogen layers beingdirectly formed on the bonding layer; wherein thenickel-chromium-nitrogen layers have porous structure, eachsilver-cerium alloy layer has a portion embedded in the porous structureof the adjacent nickel-chromium-nitrogen layers.
 2. The coated articleas claimed in claim 1, wherein one of the nickel-chromium-nitrogenlayers forms an outermost layer of the coated article.
 3. The coatedarticle as claimed in claim 1, wherein the substrate is made ofstainless steel.
 4. The coated article as claimed in claim 1, whereineach nickel-chromium-nitrogen layer has a thickness of about 40 nm-80nm.
 5. The coated article as claimed in claim 1, wherein eachnickel-chromium-nitrogen layer contains about 30%-45% nickel by atomicpercentage, about 40%-55% chromium by atomic percentage, and about5%-15% nitrogen by atomic percentage.
 6. The coated article as claimedin claim 1, wherein each silver-cerium alloy layer has a thickness ofabout 40 nm-80 nm.
 7. The coated article as claimed in claim 1, whereineach silver-cerium alloy layer contains about 20%-30% cerium and 70%-80%silver by atomic percentage.
 8. The coated article as claimed in claim1, wherein the nickel-chromium-nitrogen layers and the silver-ceriumalloy layers have a total thickness of about 2 μm-3.2 μm.
 9. The coatedarticle as claimed in claim 1, wherein the bonding layer has a thicknessof about 150 nm-250 nm.